Phase change memory with tapered heater

Abstract

An embodiment of the present invention includes a phase change memory (PCM) structure configurable for use as a nonvolatile storage element. The element includes at least one bottom electrode; at least one phase change material layer on at least a portion of an upper surface of the bottom electrode; and at least one heater layer on at least a portion of an upper surface of the phase change material layer, wherein the heater layer has a tapered shape such that an upper surface of the heater layer has a cross-sectional width that is longer than a cross-sectional width of a bottom surface of the heater layer contacting the phase change material layer.

1. A phase change memory (PCM) structure configurable for use as a nonvolatile storage element, the PCM structure comprising:
 a substrate; 
 at least one bottom electrode on at least a portion of an upper surface of the substrate; 
 at least one phase change material layer on at least a portion of an upper surface of the bottom electrode; and 
 at least one heater layer on an upper surface of the phase change material layer, wherein the heater layer has a tapered shape such that an upper surface of the heater layer has a cross-sectional width that is greater than a cross-sectional width of a bottom surface of the heater layer contacting the phase change material layer; 
 wherein the cross-sectional width of the heater layer contacting the phase change material layer is substantially equal to a cross-sectional width of the upper surface of the phase change material layer. 
 
     
     
       2. The structure of  claim 1 , further comprising at least one top electrode on at least a portion of the upper surface of the heater layer. 
     
     
       3. The structure of  claim 1 , wherein the phase change material layer has a cross-sectional width substantially similar to the cross-sectional width of the lower surface of the heater layer. 
     
     
       4. The structure of  claim 1 , wherein the cross-sectional width of the upper surface of the heater layer is approximately twice the cross-sectional width of the bottom surface of the heater layer. 
     
     
       5. The structure of  claim 1 , wherein the cross-sectional width of the bottom surface of the heater layer is approximately one-third of the original cross-sectional width of the heater layer. 
     
     
       6. The structure of  claim 1 , wherein the cross-sectional width of the upper surface of the heater layer is approximately two-thirds of the original cross-sectional width of the heater layer. 
     
     
       7. The structure of  claim 1 , wherein the heater material comprises TiN. 
     
     
       8. The structure of  claim 1 , wherein the phase change material layer comprises at least one chalcogenide. 
     
     
       9. A nonvolatile storage cell, comprising:
 at least one phase change memory (PCM) structure comprising: 
 a substrate; 
 at least one bottom electrode on at least a portion of an upper surface of the substrate; 
 at least one phase change material layer on at least a portion of an upper surface of the bottom electrode; 
 at least one heater layer on an upper surface of the phase change material layer, wherein the heater layer has a tapered shape such that an upper surface of the heater layer has a cross-sectional width that is greater than a cross-sectional width of a bottom surface of the heater layer contacting the phase change material layer; 
 wherein the cross-sectional width of the heater layer contacting the phase change material layer is substantially equal to a cross-sectional width of the upper surface of the phase change material layer. 
 
     
     
       10. An integrated circuit including at least one phase change memory (PCM) structure configurable for use as a nonvolatile storage element, the at least one PCM structure comprising:
 a substrate; 
 at least one bottom electrode on at least a portion of an upper surface of the substrate; 
 at least one phase change material layer on at least a portion of an upper surface of the bottom electrode; 
 at least one heater layer on an upper surface of the phase change material layer, wherein the heater layer is formed as a tapered homogeneous conductor structure, an upper surface of the heater layer having a cross-sectional width that is greater than a cross-sectional width of a bottom surface of the heater layer contacting the phase change material layer.